When comparing Genome2D vs FlatRedBall, the Slant community recommends FlatRedBall for most people. In the question“What are the best 2D game engines?”FlatRedBall is ranked 47th while Genome2D is ranked 56th. The most important reason people chose FlatRedBall is:

Just check the commit frequency on github :)
https://github.com/vchelaru/FlatRedBall/commits/master
Plus Victor takes community input seriously and is known to shift around priorities based on the pressing needs of the community

Ranked in these QuestionsQuestion Ranking

Pros

Pro

Lightning fast

It's the fastest gpu-based framework out there for flash. It's beautifully optimised. It has very low rendering latency, low level OpenGL calls that other tech simply cannot do (ie Unity) due to Stage3D, and thus can render a lot more data quicker

Pro

Cross-platform mobile, desktop and web

And with the HTML5 export, it also potentially supports development for the Wii U :)

Pro

Haxe!

Haxe is a strictly typed programming language that saves development time but still compiles high performance executables, and can build for tons of different platforms (flash, c++, html5, java, c#, etc.)

Pro

Access to direct draw features

Has access to direct draw features so you can make you own rendering structures (scene graphs etc).

Pro

Component based architecture

Pro

Continually improving and open source

Plus Victor takes community input seriously and is known to shift around priorities based on the pressing needs of the community

Pro

Very easy to use

Simplifies routine tasks such as adding entities and files to the game, or tuning parameters, via the FRB Editor called Glue

Pro

Great community

Very active chat on gitter: https://gitter.im/vchelaru/FlatRedBallVictor (the creator of the engine) is available throughout the day to answer questions and solve any problems that may arise, along with the rest of the community members who are ready to assist in any way they can.

Pro

Extensive documentation

http://flatredball.com/documentation/Very good documentation not only regarding the API details, but also lots of tutorials covering different aspects of using FRB, either on the code-side or on using any of its tools.

Cons

Con

Lacks documentation

The API documentation is minimal, there's not many tutorials and the ones that are there are very small and only cover the basics. If you want to learn how to properly use it, you have to ask the community or read the source code and figure it out.

Con

Not too many games to showcase it

Con

Slow development rate

Con

The editor's UI looks dated

Although functional, doesn't look as flashy as Unity for example, which may put some people off.